The file structure is essentially the same. You can create a new Libsass project, then move your styles and htlm over manually. Libsass does not require Ruby so you dont need the gemfile or and .rb files. You will need to add a gruntfile. I made a quick Notable annotation to point out the difference https://www.notableapp.com/posts/41d5dd009b7823cca41abaa8effd4fbd801aa09f

In case you were using Compass mixins, you will need to add to the Foundation bower.json file that is created when you created the project with the CLI. Follow the instructions here, and you can have Compass right inside your project.